A known inkjet recording apparatus records an image on a recording medium by ejecting ink stored in an ink storage chamber of an ink cartridge. Among various types of ink cartridges, an ink cartridge includes a member, e.g., a float, which is movable within its ink storage chamber in accordance with an amount of ink remaining in the ink storage chamber.
In such an inkjet recording apparatus, a change in viscosity of ink stored in the ink storage chamber of the ink cartridge may cause clogging in the nozzles and/or deterioration of image recording quality. In order to avoid an occurrence of such problems, for example, the inkjet recording apparatus calculates the viscosity of ink stored in the ink storage chamber. The float is retained by a restriction member with being submerged in ink. The calculation is performed by measuring a time elapsed until a detector reaches a released position due to a buoyant force of the float from a release of the float. In order to move the detector by access from the outside of the ink cartridge, a movable member needs to be provided for transmitting an external force exerted from the outside of the ink cartridge to the detector by movement of the movable member. The movable member is generally disposed in an internal space of an ink outlet, which extends between the ink storage chamber and the outside of the ink cartridge in order to allow ink to flow to the outside of the ink cartridge from the ink storage chamber. In this arrangement, there is a gap between the movable member and a wall of defining the internal space.